Various mobile architectures include a macro cell having smaller cells found within these macro cells. These smaller cells, also referred to as low power nodes, such as relay nodes, pico cells, femto cells among others, can be used to improve the cell edge performance and increase average cell throughput. Pico cells and femto cells are basically evolved node Bs (eNBs) with low transmission power and are generally connected to a macro cell through a wired backhaul connection. Relay nodes are typically low-transmit power eNBs without a direct backhaul connection to the macro node.
UEs connected to network via a low power node such as pico cell or femto cell or relay node may be however, exposed to significant inter-cell interference. In order to manage inter-cell interference, one technique is to use an inter-cell interference coordination (ICIC) technique, also called an almost blank subframe (ABS). The ABS occurs in some heterogeneous deployments where a cluster of cells with large and small coverage areas co-exist in a geographical region. The ABS is a normal subframe where an average transmit power of the physical downlink shared channel (PDSCH) physical resource bearer (PRB) is set to a very low power. The average transmit power during the ABS transmission is set by the eNB.
According to the Third Generation Partnership Project (3GPP), Long Term Evolution (LTE) Release 10 specifications, a UE can be configured by the network to send a separate channel quality indicator (CQI) feedback for ABS and non-ABS transmissions.